Femtosecond laser microstructuring of hot-isostatically pressed zirconia ceramic

Densely sintered zirconia ceramics—especially hot-isostatically pressed forms of zirconia ceramics like hot-isostatically pressed yttria-stabilized tetragonal zirconia polycrystal (HIP Y-TZP)—have the potential of superseding conventional dental material in the field of dental restorations. Strong tool wear can only be prevented by nonmechanical processes like laser-based approaches. Ultrafast lasers can avoid crystal structure transformations in the bulk material and thus retain the unique material characteristics, which makes them an ideal tool for HIP ceramic dental restoration manufacturing units. Laser processing of Y-TZP in the femtosecond regime enables most precise microstructuring even compared to picosecond pulse ablation. An adaptation of typical parameters—including the laser fluence (resulting from laser pulse as well as focusing parameters) and pulse overlapping (resulting from processing speed and multiple iterations)—strongly influences the results with regard to process yield and quality. The use of a superficial water layer during processing enhances the quality of results for certain ablation strategies and influences potentially hazardous emission of particulate matter from the samples. Applications in connection with dental crowns and bridges include cutting of their complete shape from solid material, and finishing steps, as well as surface structuring for the purpose of optimized cement adhesion.